U.S. patent application number 11/082297 was filed with the patent office on 2006-10-12 for apparatus and methods for spinal implant with dynamic stabilization system.
Invention is credited to Thomas A. Foster, David M. Hooper, David J. Krueger, Margaret E. Mitchell.
Application Number | 20060229608 11/082297 |
Document ID | / |
Family ID | 36589285 |
Filed Date | 2006-10-12 |
United States Patent
Application |
20060229608 |
Kind Code |
A1 |
Foster; Thomas A. ; et
al. |
October 12, 2006 |
Apparatus and methods for spinal implant with dynamic stabilization
system
Abstract
A spinal implant provides support for desired parts of the
spine. The implant can provide support in both fusion and
non-fusion situations. The spinal implant includes an implant rod
and fasteners for coupling or fastening the implant rod to the
affected regions of the spine via the pedicles of the affected
vertebrae). The implant rod includes a flexible portion and rigid
end portions. The fasteners couple the end portions of the rod to
the pedicles in the affected level. The flexible portion can take a
variety of shapes, such as non-helical, multi-curve springs. One
may combine several implant rods to provide an overall implant for
more than one level of the spine. The implant can allow desired
motion while tending to limit undesirable motion, thus protecting
areas of the diseased or injured spine, such as the nucleus
pulposus or anulus fibrosis. Furthermore, the implant can provide a
combination of rigid and flexible support, as desired. One may
manufacture the implant using a variety of materials, such as
stainless steel, titanium, or titanium Beta C.
Inventors: |
Foster; Thomas A.; (Boulder,
CO) ; Hooper; David M.; (Austin, TX) ;
Mitchell; Margaret E.; (Cedar Park, TX) ; Krueger;
David J.; (Cedar Park, TX) |
Correspondence
Address: |
ROBERT DEBERARDINE;ABBOTT LABORATORIES
100 ABBOTT PARK ROAD
DEPT. 377/AP6A
ABBOTT PARK
IL
60064-6008
US
|
Family ID: |
36589285 |
Appl. No.: |
11/082297 |
Filed: |
March 17, 2005 |
Current U.S.
Class: |
128/898 ;
606/254; 606/257; 606/261; 606/907 |
Current CPC
Class: |
A61B 17/7004 20130101;
A61B 17/7011 20130101; A61B 17/705 20130101; A61B 17/7026
20130101 |
Class at
Publication: |
606/061 |
International
Class: |
A61F 2/30 20060101
A61F002/30 |
Claims
1. An implant, comprising: a first rod, comprising a non-helical,
multi-curve flexible portion coupled to a respective rigid portion
at each end; and a plurality of fasteners coupled to the first rod,
the plurality of fasteners configured to fasten the first rod to
vertebrae.
2. The implant according to claim 1, wherein the plurality of
fasteners comprises a plurality of pedicle screws configured to
couple the first rod to vertebrae.
3. The implant according to claim 1, wherein the first rod is
preloaded before being fastened to the vertebrae.
4. The implant according to claim 1, further comprising a second
rod adjacent to the first rod, wherein the second rod comprises a
flexible portion.
5. The implant according to claim 1, further comprising a second
rod adjacent to the first rod, wherein the second rod comprises a
rigid rod.
6. The implant according to claim 1, further comprising a second
rod coupled to the first rod, wherein the second rod comprises a
rigid rod or a flexible rod.
7. The implant according to claim 6, further comprising a sleeve,
wherein the sleeve couples the first rod to the second rod.
8. The implant according to claim 1, wherein the implant tends to
limit shear and torsion movements in the spine, and wherein
limiting the shear and torsion movements tends to protect the
nucleus pulposus and anulus fibrosis.
9. The implant according to claim 2, wherein the rigid portions
extend outwardly from the flexible portion.
10. The implant according to claim 2, wherein the rigid portions
extend inwardly from the flexible portion.
11. A system for supporting vertebral bodies in a spine,
comprising: an implant rod, comprising: a non-helical serpentine
spring portion, having first and second ends; and first and second
rigid portions coupled, respectively, to the first and second ends
of the spring portion.
12. The system according to claim 11, wherein the implant tends to
support flexion-extension of the spine, and wherein the implant
tends to limit shear and torsion movements in the spine.
13. The system according to claim 11, wherein limiting the shear
and torsion movements in the spine tends to protect the nucleus
pulposus and anulus fibrosis, and allows healing of the spine.
14. The system according to claim 11, further comprising first and
second fasteners configured to couple the implant rod to a pair of
vertebrae; wherein the first rigid portion couples to the first
fastener, and wherein the second rigid portion couples to the
second fastener.
15. The system according to claim 14, wherein the first fastener
comprises a first screw configured to couple to a first pedicle in
the spine, and wherein the second fastener comprises a second screw
configured to couple to a second pedicle in the spine.
16. The system according to claim 11, wherein the first rigid
portion comprises at least one orientation mechanism, and wherein
each orientation mechanism is configured to facilitate orienting
the spring in a desired direction.
17. The system according to claim 16, wherein each orientation
mechanism comprises a flat portion.
18. The system according to claim 16, wherein the implant rod
further comprises: a first transition portion coupled to the first
end of the spring portion and to the first rigid portion; and a
second transition portion coupled to the second end of the spring
portion and to the second rigid portion.
19. A method of producing a spinal implant, the method comprising
forming an implant rod from a block of material, wherein the rod
comprises a non-helical, multi-curve flexible portion coupled to
first and second rigid portions.
20. The method according to claim 18, wherein the block of material
comprises titanium Beta C.
20. The method according to claim 18, wherein the spinal implant
comprises a multi-level implant.
21. The implant according to claim 1 wherein the first rod
comprises titanium Beta C.
Description
TECHNICAL FIELD
[0001] The inventive concepts relate generally to spinal implants.
More particularly, the invention concerns apparatus and associated
methods for spinal implants with dynamic stabilization systems that
can provide flexible or rigid support, as desired.
BACKGROUND
[0002] Modern spine surgery often involves the use of spinal
implants to correct or treat various spine disorders or to support
the spine. Spinal implants may help, for example, to stabilize the
spine, correct deformities of the spine, facilitate fusion, or
treat spinal fractures. Typical spinal implants either provide
flexible or rigid (i.e., in a fusion procedure) support for the
affected regions of the spine. Furthermore, they either limit
movement in the affected regions in virtually all directions (for
example, in a fused region), or they fail to limit undesired
movement of the spine while allowing the desired movement. A need
exists for a spinal implant that provides flexible or rigid
support, as desired, while allowing desired movement of the
affected levels of the spine and limiting the undesired movement of
those levels.
SUMMARY
[0003] The inventive concepts relate to apparatus and methods for
spinal implants with dynamic stabilization systems. In one
exemplary embodiment, an implant includes a rod with a multi-curve
flexible portion. Each end of the flexible portion couples or
connects to a respective rigid portion of the rod. A pair of
fasteners fasten the rod to vertebrae (e.g., at a desired level of
the spine).
[0004] In another exemplary embodiment, a system for supporting
vertebral bodies in a spine includes an implant rod, and a pair of
fasteners. The implant rod includes a serpentine spring portion
with two ends. Each of the ends of the spring portion couples or
connects to a respective pair of rigid portions of the rod.
Fasteners couple the implant rod to a pair of spinal vertebrae.
[0005] In yet another exemplary embodiment, a method of producing a
spinal implant includes forming an implant rod from a block of
material (such as titanium Beta C). The block of material is formed
so as to generate a multi-curve flexible portion with two ends. The
ends of the flexible portion of rod are formed so as to couple,
respectively, to a pair of rigid portions of the rod.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The appended drawings illustrate only exemplary embodiments
of the invention and therefore should not be considered or
construed as limiting its scope. Persons of ordinary skill in the
art who have the benefit of the description of the invention
appreciate that the disclosed inventive concepts lend themselves to
other equally effective embodiments. In the drawings, the same
numeral designators used in more than one drawing denote the same,
similar, or equivalent functionality, components, or blocks.
[0007] FIG. 1 shows an implant rod according to an illustrative
embodiment of the invention.
[0008] FIG. 2 illustrates an implant rod according to another
illustrative embodiment of the invention.
[0009] FIG. 3 depicts an isometric view of an implant according to
an exemplary embodiment of the invention implanted to support a
portion of a spine.
[0010] FIG. 4 shows a side view of the implant shown in FIG. 3.
[0011] FIGS. 5A-5C illustrate examples of implant configurations in
illustrative embodiments according to the invention.
[0012] FIGS. 6A-6B depict multi-level implant rods according to
exemplary embodiments of the invention.
[0013] FIG. 7 shows an implant rod according to an exemplary
embodiment of the invention.
[0014] FIGS. 8A-8B illustrate an implant rod 700 according to
another exemplary embodiment of the invention.
[0015] FIGS. 9A-9B depict an implant rod according to an additional
exemplary embodiment of the invention.
[0016] FIGS. 10A-10B show an implant rod 900 according to another
embodiment of the invention.
[0017] FIGS. 11A-11B illustrate an implant according to an
exemplary embodiment of the invention implanted to support a
portion of a spine.
[0018] FIGS. 12A-12C depict implant rods with orientation
mechanisms according to illustrative embodiments of the
invention.
DETAILED DESCRIPTION
[0019] The disclosed novel concepts relate to spinal implants with
dynamic stabilization systems. In a dynamic stabilization
procedure, the surgeon typically attaches an implant construct to
either side of the affected vertebral level. The implant serves the
function of stabilizing the spine. The inventive implants allow a
controlled range of motion in some directions (or allow some types
of motion), while inhibiting or limiting motion in other directions
(or inhibit or limit other types of motion). The implants allow the
patient to maintain flexibility and a functioning spine. The
implant can also protect the loading at a level in the early stages
of degeneration and allow healing of the soft tissues and bony
structures at that level.
[0020] The implants can also allow flexibility in one or more
levels, while supporting fusion in one or more other levels. Fusion
surgery (for example, in the case of degenerative vertebral
disease), allows fusion of adjacent vertebrae. Although the fusion
reduces the pain, it also limits or reduces functionality of the
spine, and may affect the stresses at levels superior and/or
inferior to the fused level(s). By using the appropriate
combination of rigid and flexible implant rods, the surgeon can
provide flexibility in one or more levels and provide fusion in one
or more other levels, as desired. The implant allows selective
control of the loads and ranges of motion at the levels adjacent to
a fusion and may help to prevent adjacent disc disease.
[0021] The novel spinal implants provide many advantages over
conventional implants, as described below in detail. The spinal
implants tend to allow desired movements of the affected parts of
the spine, while tending to limit undesired movement of those
regions. For example, the implants allow controlled flexion or
extension, which may benefit the spine and promote nutritional
exchange in the disc. At the same time, the implants limit or tend
to disallow torsion or shear, movements considered harmful to the
affected parts of the spine, which may include the nucleus pulposus
or annulus fibrosis.
[0022] The disclosed implants allow rigid or flexible support for
the spine, as desired (rather than providing either rigid or
flexible support exclusively). The disclosed implants also offer
relative ease of manufacturing. One may manufacture implants with
low-profile springs or flexible regions, with no articulating
pieces (no joints) that would generate wear debris.
[0023] The implants provide a flexible mechanism for providing
support for one or more levels of the spine, as desired. The
surgeon may vary the type of support from one level to another. For
example, for one level, the surgeon may use the implant to provide
flexible support, while for another level, the implant may provide
rigid support. As another example, the surgeon may use alternating
flexible and rigid segments of the implant to provide the desired
support for the spine.
[0024] The implants can also combine rigid and flexible rods in a
modular fashion to support both fusion and non-fusion applications.
The ability to custom-fit the implants to the patient's needs
provides the surgeon and the patient with an improved option over
conventional implants. The disclosed implants also allow preloading
of the implant to create distraction or lordosis of the
instrumented level(s) of the spine (i.e., help to produce a desired
profile of the affected regions of the spine).
[0025] FIG. 1 shows an implant rod 100 according to an illustrative
embodiment of the invention. Implant rod 100 includes a flexible or
spring region (or serpentine portion or member) 103, transition
portions or areas 106 (optional), and end or rigid portions 109.
Spring region 103 has a multi-curve or complex shape, i.e., it
includes more than one curve (for example, an "S" shape, rather
than a simple "C" shape).
[0026] Spring portion 103 couples to rigid portions 109 via
optional transition portions 106. Transition portions 106 serve to
reduce the stress concentrations between the spring portion 103 and
the rigid end portions 109. Note, however, that one may omit
transition portions 106, depending on a variety of factors, such as
the type of materials used, the desired strength and profile of the
implant, etc., as desired. In the embodiment shown, spring portion
103 has a curvilinear, non-helical shape.
[0027] Note that spring portion 103 has two curved portions (one
portion with the shape of a "U" coupled to a portion shaped like an
upside-down "U"). As described below in detail, however, one may
use a variety of other shapes and configurations, as desired.
[0028] FIG. 2 illustrates an implant rod 200 according to an
illustrative embodiment of the invention. Similar to implant rod
100 of FIG. 1, implant rod 200 includes spring portion 103,
optional transition portions 106, and end or rigid portions 109.
Spring portions 103 has a shape similar to spring portion 103 in
FIG. 1.
[0029] Spring portion 103 of rod 200 includes five curved portions.
As persons of ordinary skill in the art who have the benefit of the
description of the invention understand, one may use a wide variety
and configurations of spring portion 103, such as the number and
shape of the curved regions, as desired. The number of curves and
configuration of spring portion 103 depends on a number of factors,
such as the patient's physical size, the materials used, the degree
of flexibility desired, etc., as persons of ordinary skill in the
art who have the benefit of the description of the invention
understand.
[0030] FIG. 3 shows an isometric view of an implant according to an
exemplary embodiment of the invention implanted to support a
portion of a spine. The figure shows vertebral body 305 and
vertebral body 310. The implant uses rods 300A and 300B, one on
each side of vertebral bodies 305 and 310. Implant rods, although
similar to rods 100 and 200 (see FIGS. 1 and 2, respectively),
differ in the number of curves of their flexible or spring
portions. Note, however, that one may readily use rods with other
numbers of curves or shapes, and cross-sections, as desired, and as
persons of ordinary skill in the art who have the benefit of the
description of the invention understand.
[0031] Implant rod 300A couples to vertebral bodies 305 and 310
through a desired type of fastener, such as pedicle screws 320A and
320B. More specifically, end portions 109 of implant rod 300A
couple to pedicle screws 320A and 320B, respectively. Pedicle
screws 320A and 320B hold end portions 109 in place so that the
overall height of the implant matches the desired spacing for a
particular patient. Pedicle screws 320A and 320B also fasten
implant rod 300A to pedicles 325 (see FIG. 4 for location of
pedicles 325) of vertebral bodies 305 and 310. Pedicle screws 320C
and 320D serve similar functions with respect to implant rod
300B.
[0032] FIG. 4 illustrates a side view of the implant shown in FIG.
3. More specifically, FIG. 4 depicts implant rod 300A and pedicle
screws 320A and 320B. As noted above, one may adjust the spacing
between pedicle screws 320A and 320B (i.e., preload the implant) so
as to achieve a desired posture for the affected portion of the
spine. During the procedure, the surgeon may push towards each
other (compression) pedicle screws 320A and 320B, or pull them away
from each other (distraction). End portions 109 of implant rod 300A
slide within the respective pedicle screws 320A and 320B. Once the
surgeon has achieved the desired spacing or preloading, he or she
tightens cap screws 340A and 340B. Cap screws 340A and 340B
securely hold end portions of rod 300A in place and thus maintain
the desired spacing between vertebral bodies 305 and 310.
[0033] As noted above, the disclosed implants can support both
fusion and non-fusion situations, in a wide variety of
configurations. FIGS. 5A-5C depict examples of implant
configurations in illustrative embodiments according to the
invention. In FIG. 5A, implant 400A includes rod 300. Rod 300
constitutes a flexible rod, as described above. It can provide
support for a non-fusion situation.
[0034] In FIG. 5B, implant 400B includes rod 300A and rod 300B.
Both rod 300A and rod 300B constitute flexible rods, and can
provide flexible support for two vertebral levels
(flexion-flexion). Note that one may use more than two rods, as
desired, and as persons of ordinary skill in the art who have the
benefit of the description of the invention understand.
[0035] Referring to FIG. 5B, note that one may substitute a rigid
rod for flexible rod 300A or 300B, as desired, thus providing
support in a fusion situation. FIG. 5C illustrates such a
configuration (flexion-rigid). More specifically, one substitutes
rigid rod 405 for flexible rod 300B in order to produce implant
400C in FIG. 5C. Implant 400C provides support for a non-fusion
level as well as support for a fusion level. Note, however, that by
using an appropriate number and configuration of rods, one may
support one or more non-fusion levels, one or more fusion levels,
or both, as desired, and as persons of ordinary skill in the art
who have the benefit of the description of the invention
understand.
[0036] Ordinary, one may construct multi-level implant rods from
one piece of material. In other words, one may process a single
piece of material to produce a multi-level implant rod.
Alternatively, one may construct multi-level implants by joining
implant rods with a mating or coupling mechanism, as desired. FIGS.
6A-6B illustrate multi-level implant rods according to exemplary
embodiments of the invention. FIG. 6A shows multi-level implant rod
500. Implant rod 500 includes rod 300A and rod 300B. Mating or
coupling member 505 couples one end portion of implant rod 300A to
an end portion 109 of implant rod 300B. In FIG. 6A, coupling member
505 constitutes a sleeve, although one may use other mechanisms, as
persons of ordinary skill in the art who have the benefit of the
description of the invention understand.
[0037] FIG. 6B shows a cut-away view of implant 500 of FIG. 6A.
Coupling member 505 may have an appropriate size or length so as to
allow desired spacing between rod 300A and rod 300B. By adjusting
the spacing between rod 300A and rod 300B, one may fit the implant
to the patient's spine or provide angulation between members 300A
and 300B, as desired.
[0038] One may use a variety of configurations, shapes, and
materials for the implants, including the implant rods. FIG. 7
shows an implant rod 600 according to an exemplary embodiment of
the invention. Similar to the implant rods described above, implant
rod 600 includes flexible portion 605, optional transition portions
106, and end or rigid portions 109. Rather than a curvilinear
spring or flexible portion, spring portion 605 has an angular or
substantially angular configuration. More specifically, in
embodiment 600, spring portion 605 has the shape of an "M." As in
the above curvilinear designs, this angular configuration may
include two or more angled sections, rather than the three angles
shown.
[0039] FIGS. 8A-8B illustrate an implant rod 700 according to
another exemplary embodiment of the invention. FIG. 8A shows an
isometric view of implant rod 700. Similar to the implant rods
described above, implant rod 700 includes flexible portion 705,
optional transition portions 106, and end or rigid portions 109.
Flexible portion 705 has an annular, circular, or elliptical shape
(e.g., a loop) of desired proportions. FIG. 8B depicts a side view
of implant 700.
[0040] FIGS. 9A-9B illustrate an implant rod 800 according to
another exemplary embodiment of the invention. FIG. 9A shows an
isometric view of implant rod 800. Like the implant rods described
above, implant rod 800 includes flexible portion 805, and end or
rigid portions 109. Optionally, implant rod 800 may include
transition portions 106, as desired. Flexible portion 805 includes
one or more "S"-shaped curves of desired shapes and orientations.
For example, the embodiment shown includes three "S"-shaped curves,
with the two outermost curves in one orientation, and the middle
curve in an opposing orientation. Alternatively, the "S" shaped
curve may include three or more curved regions, rather than the two
("U" and inverted "U"). Also, the design may have two, four, or
more curved sections (rather than the three curved sections shown).
FIG. 9B depicts a side view of implant 800.
[0041] FIGS. 10A-10B illustrate an implant rod 900 according to
another embodiment of the invention. FIG. 10A shows an isometric
view of rod 900, whereas FIG. 10B depicts a side view.
[0042] Rod 900 includes spring or flexible portion 103, optional
transition portions 905, and end or rigid portions 910. Spring
portion 103 couples to rigid portions 910 via transition portions
905. Transition portions 905 provide a relatively rigid mechanism
for coupling spring portion 103 to the rigid end portions 910, as
desired.
[0043] In the embodiment shown, spring portion 103 has a
curvilinear, non-helical shape. Note, however, that spring portion
103 may have other shapes and configurations, as desired, and as
persons of ordinary skill in the art who have the benefit of the
description of the invention understand. For example, spring
portion 103 may have any of the shapes shown in FIGS. 7-9.
[0044] Rigid portions 910, rather than extending radially outward
(see, for example, FIGS. 1-2) from transition portions 905, bend or
deflect towards spring portion 103. As FIG. 10B shows, rigid
portions 910 may deflect in a downward or upward direction (or a
combination of the two, one for each rigid portion) from the
horizontal axis of rod 900, as desired. This configuration allows
the rod to be applied when the pedicle screws are closely
positioned or when an offset configuration is desired. Furthermore,
rigid portions 910 provide a mechanism for preloading or physically
configuring the geometrical properties of implant 900.
[0045] FIG. 11A shows a side view of an implant according to an
exemplary embodiment of the invention implanted to support a
portion of a spine. The figure shows vertebral body 305 and
vertebral body 310, having pedicles 325. The implant uses rod 900,
coupled to vertebral bodies 305 and 310. The implant includes
another rod on the opposite side of vertebral bodies 305 and 310
(not shown in FIG. 11A).
[0046] Implant rod 900 couples to vertebral bodies 305 and 310
through pedicle screws 320A and 320B. More specifically, end
portions 910 of implant rod 900 couple to pedicle screws 320A and
320B, respectively. Pedicle screws 320A and 320B hold end portions
910 in place so that the overall height of the implant matches the
desired spacing and loading for a particular patient. Pedicle
screws 320A and 320B also fasten implant rod 900 to pedicles 325 of
vertebral bodies 305 and 310.
[0047] The surgeon can adjust the distance between the vertebral
bodies 305 and 310 by preloading implant rod 900, as described
above. Once the adjustment has been made, the surgeon can use
pedicle screws 320A and 320B to secure rod 900, as described above.
FIG. 11B shows another view of the implant in FIG. 11A. FIG. 11B
shows details of the arrangement of the pedicle screws with respect
to rod 900 and end portions 910.
[0048] To assist in orientation and securing rods according to
various embodiments of the invention, one may use a variety of
orientation aids/mechanisms or location features. FIGS. 12A-12C
show implant rods with orientation mechanisms according to
illustrative embodiments of the invention. Persons of ordinary
skill in the art who have the benefit of the description of the
invention understand that one may use any of the varieties of the
spring portion, described above, with the orientation and location
features, as desired.
[0049] FIG. 12A shows a rod 1000A. Rod 1000A includes spring
portion 103, optional transition portions 106, and end portions
109. Each end portion 109 has a flat (or substantially flat) region
1005 that allows orientation of rod 1000A (and hence spring portion
103) with respect to the affected portion of the spine.
[0050] Note that one may use a wide variety and configuration of
orientation mechanisms, as desired. For example, FIG. 12B shows a
rod 1000B, with spring portion 103, optional transition portions
106, and end portions 109. Each of end portions 109 includes a pair
of flat (or substantially flat) regions 1010, disposed on opposing
side of end portion 109.
[0051] As another example, FIG. 12C shows a rod 1000C. Rod 1000C
includes spring portion 103, optional transition portions 106, and
end portions 109. Each end portion 109 has a plurality of flat (or
substantially flat) regions 1015 that allows orientation of rod
1000C (and hence spring portion 103) with respect to the affected
portion of the spine. In rod 1000C, each of end regions 109 has six
flat regions 1015, although one may use other numbers, as
desired.
[0052] Note that, rather than using flat regions as described
above, one may use other mechanisms, as desired, and as persons of
ordinary skill in the art who have the benefit of the description
of the invention understand. For example, one may use dimples,
grooves, or other indicators of orientation. Furthermore, one may
use various numbers of such indicators, as desired.
[0053] As noted, one may manufacture the disclosed implants
(including the implant rods) from a variety of materials. For
example, one may use stainless steel, titanium, other metals, or
polymers, as desired. In one embodiment, one may use titanium Beta
C, a titanium alloy having the composition Ti-3Al-8V-6Cr-4Mo-4Zr
(or similar compositions, as desired). Titanium Beta C may be
solution treated at 815.degree. C., and aged at 565.degree. C., or
may be treated to other conditions to achieve the desired material
characteristics.
[0054] Titanium Beta C provides relatively high resistance to
fatigue. One may manufacture the implant rods and the pedicle
screws from titanium Beta C to take advantage of that property.
Using titanium Beta C helps to provide relatively robust,
fatigue-resistant implants with improved longevity and performance
characteristics, given the ability to vary the mechanical
properties of this titanium alloy by varying the heat treat
parameters
[0055] As noted above, the disclosed implants offer relative ease
of manufacturing as an advantage. To manufacture the implants, one
may use a lathe and wire EDM to fabricate the implant by shaping
and forming a piece or block of material. Advantageously, one may
manufacture each implant from a monolithic piece of material, thus
reducing joints and associated manufacturing expenses. As an
alternative, one may fabricate the implants by using mill
processes, as desired.
[0056] Various modifications and alternative embodiments of the
invention in addition to those described here will be apparent to
persons of ordinary skill in the art who have the benefit of the
description of the invention. Accordingly, the manner of carrying
out the invention as shown and described are to be construed as
illustrative only. Persons skilled in the art may make various
changes in the shape, size, number, and/or arrangement of parts
without departing from the scope of the invention described in this
document. For example, persons skilled in the art may substitute
equivalent elements for the elements illustrated and described
here, or use certain features of the invention independently of the
use of other features, without departing from the scope of the
invention.
* * * * *